Histological and ultrastructural observation of developing miniature pig salivary glands

Objectives:To observe the sequential histological and ultrastructural features of different development stages of miniature pig salivary glands and identify the embryonic day of the different development stages.Methods:E40, E60, E80, E95 miniature pig embryo and the P0 miniature pig were selected, the parotid gland and submandibular gland were removed from the E60, E80, E95 miniature pig embryo and the P0 miniature pig, the whole head were cut from the E40 embryo. Serial sections were made for all the samples. The sections were stained with Hematoxylin and Eosin and observed using light microscope. The Ultrastructural features of salivary gland samples were observed using transmission electron microscope. Results:The development process of miniature pig salivary gland could be divided into 5 stages based on the features of development, including Initial Bud stage (E40), Pseudoglandual stage (E60),Canalicular stage (E80),Terminal Bud stage (E95), Mature stage (P0) referring the mouse salivary gland development stages. In the same embryonic day, earlier development of the submandibular gland was found compared with parotid gland development. The histological features were confirmed in the ultrastructural level.Conclusions:This study presents for the first time dynamic morphological changes of developing salivary glands in the miniature pig including sequential histological and ultrastructural features and the embryonic day of the different development stages. The development of submandibular gland is earlier than the development of parotid gland.